Exemplary embodiments pertain to the art of electric machines and, more particularly, to a method of operating an electric machine having an integrated coolant level sensor.
Electric machines produce work from electrical energy passing through a stator to induce an electro-motive force in a rotor. The electro-motive force creates a rotational force at the rotor. The rotation of the rotor is used to power various external devices. Of course, electric machines can also be employed to produce electricity from a work input. In either case, electric machines are currently producing greater outputs at higher speeds and are being designed in smaller packages. The higher power densities and speeds often result in harsh operating conditions such as high internal temperatures, vibration and the like. Accordingly, many conventional electric machines include coolant systems that are configured to lower temperatures of internal components.
Coolant systems include airflow systems, water based coolant systems, oil based coolant systems and glycol based coolant systems. Airflow systems typically include fans that direct a convective airflow through the electric machine. Water based coolant systems typically circulate water through a jacket that extends about the electric machine. Oil based systems introduce oil or other forms of coolant directly into the electric machine. The coolant flows onto, for example, stator windings and collects in a lower portion of the machine. The coolant is then directed to a heat exchange member. The heat exchange member extracts entrained heat from the coolant. The coolant is then passed back through the electric machine.